| This research work is focused on the coordination chemistry of five closely related guanidinate ligands. A series of trivalent lanthanide derivatives of the L1 ligand were also prepared and structurally characterized in this work. Chapter 1 gives a brief introduction to the chemistry of metal guanidinate complexes.;Chapter 2 reports on the synthesis, structure and reactivity of chromium(II) complexes derived from the bulky L1 and L4 ligands. Treatment of CrCL2 with [KL1 · 0.5PhMe] (1) afforded the mononuclear Cr(II) bis(guanidinate) complex [Cr(L1)2] (3). Reaction of CrCL 2 with [LiL4(Et2O)] (2) resulted in the isolation of ate--complex [Cr(L4)(mu--Cl) 2Li(THF)(Et2O)] (4). Recrystallization of 4 from toluene gave neutral, dimeric [{Cr(L4)(mu--Cl)} 2] (5). The reaction chemistry of the Cr(II) complex 3 and 4 was studied. Treatment of 3 with I2, PhEEPh (E = S, Se, Te), 1--AdN3 (1--Ad = 1--adamantyl) gave the corresponding mixed--ligand Cr(III) complexes, namely [Cr(L1)2I] (6) and [Cr(L 1)2(EPh)] [E = S (7), Se (8), Te (9)] and Cr(IV) complex [Cr(L1)2{N(1--Ad)}] (10). Besides, the reaction of 4 with NaOMe resulted in the isolation of the Cr(II) methoxide--guanidinate complex [{Cr(L 4)(mu--OMe)}2] (11).;Chapter 3 deals with the synthesis, structure and reactivity of lanthanide(II) complexes supported by the L1, L2, L 3 and L5 ligands. Lanthanide(II) guanidinate complexes were prepared by the reactions of an appropriate lanthanide diiodide with the corresponding potassium guanidinate complexes [KL1 · 0.5PhMe] (1), [KL2(THF)0.5]n (12), KL3 (13) and [KL5(THF) 2] (14). Reaction of EuI2(THF)2 with 1 gave the homoleptic complex [{Eu(L1)(mu--L 1)}2] (15). Metathesis reactions of LnI 2(THF)2 (Ln = Yb, Eu) with 12 and 13 led to the isolation of [{Ln(L2)(mu--L2)} 2 · nC6H14] [Ln = Eu, n = 2 (16); Ln = Yb, n = 0 (17)], [Yb(L2)2(THF) 2] (18) and [Ln(L3)2(THF) 2 · 0.25C6H14] [Ln = Eu (19), Yb (20)]. Direct reaction of SmI2(THF)2 with 13 yielded the iodide bridged Sm(II) complex [{Sm(L 3)(mu--I)(THF)}2] (21), whilst reaction of SmI2(THF)2 with 14 gave homoleptic [Sm(L 5)2] (22). The reaction chemistry of 1 5, 18, 20 and 22 as reducing agents was examined.;Chapter 4 describes the preparation and structural characterization of lanthanide(III) complexes derived from L1. A series of homoleptic lanthanide(III) tris(guanidinate) complexes [Ln(L1)3] [Ln = Ce (30), Pr (31), Gd (32), Tb (33), Ho (34), Er (35), Tm ( 36)] were prepared by the reactions of an appropriate LnCL3 with three molar equivalents of 1. Treatment of CeCL 3 and LuCL3 with two equivalents of 1 gave the corresponding chloride bridged guanidinate complexes [{Ln(L 1)2(mu--Cl)}2] [Ln = Ce (37), Lu (38)]. (Abstract shortened by UMI.). |
